The Chicago Fire Department was hosing down South Side bridges that had expanded during a recent spike in temperatures, fire officials said Thursday.

“It's a regular occurrence when the heat soars,” said Peter Scales, a spokesman with the Chicago Department of Transportation, in an emailed statement. “We cool them down regularly in the high temperatures because when the heat expands the bridge steel, it is often difficult to lock the leaves back into place.”

The bridges over the Calumet River at 95th and 100th streets were cooled over the past three days, and traffic was rerouted around them, Scales said.